Rotator



Oct. 11, 1927. L. P' BURGESS ET AL 1,644,913

ROTATOR Filed Jan. 19. 1924 3 Sheets-Sheet 2 Oct. 1 1 1927.

L. P. BURG ESS ET AL ROTATOR 3 Sheets-Sheet 3 Filed Jian. 19. .1924

Patented Oct. 11, 1927.

UNITED STATES PATENT OFFICE.

LYSLE P. BURGESS AN D EDWARD E. STEVENSON, F LOS ANGELES, CALIFORNIA, AS-

SIGNORS TO D. @c B. PUMP AND SUPPLY COMPANY, OF LOS ANGELES, CALIFORNIA,

A CORPORATION OF CALIFORNIA.

Ro'raron.

Application filed January 19, 1924. Serial No. 687,279.

This invention has to do generally with rotators and more particularly with rotators used in connection with mechanisms Where the reciprocating motion of a given member is to be accompanied by a partial rotation thereof.

As will be fully explained in the body of the speciiication, in our device the rotation of such a member is accomplished by the differential loading of the member during its reciprocation; or in consequence of its inertia when subjected to sudden, positive acceleration or to a change in its direction of longitudinal movement.

The device may be used in many and various situations, and while it may be applied with advantage to either a vertically or horizontally reciprocating member, it has certain distinctive features which render it particularly vvell adapted to rotate the vertically reciprocating rods and plungers of deep well pumps. For thepurpose of more definitely describing the invention and pointing out the novel features and advantages of a physical embodiment thereof, we have illustrated and will describe the invention as applied to this latter use, but the drawings and description are to be considered merely as illustrative of and not restrictive on the invention.

It is well recognized by those skilled in the art that pump plungers and sucker rods, which ext-end from said plu-ngers to the reciprocating mechanism above, should be rotated periodically. Hence there is no need of here setting forth a full discussion of why such movement is desired, except to briefly state that it assures equal distribution of wear on pump plungers and working barrels, eliminates the danger of the plunger and barrel from becoming scored by foreign matter, prevents sucker rods from becoming unscrewed, reduces the likelihood oi" the pump sanding up, and gives both plunger and sucker rod, where the latter pass through the upper stufling box', the characteristics of self-cleaning devices by preventing the accumulation of foreign matter thereon. It will be seen that by reason of these accomplishments an eiici'ent rotating mechanism has great economic value in that it greatly reduces the cost of upkeep, the labor and expense of repair, and the loss of production which is attendant upon such repair.

As far as we are aware, all prior rotators depend upon the variable angularity between walking beams and sucker rods for accomplishing the rotation ot said rods, the rotary movement being transmitted to the rods through ratchet and pawl systems. As distinguished from such a method, We provide. means whereby the rods'have relative longitudinal movement with respect to walk- 1ng beams, and it is by this relative movement that we accomplish the desired rod rotation.

Briefly described, the device comprises a rotor clamped to the polish rod and rotatably supported on top an intermediate resillent member carried on or suspended fromthe beam, and it is through the lexure of this member (caused by dierential loadmg or the inertia of the rods) that the relative longitudinal movement between rod and beam is accomplished. Through a novel arrangement of cams on the rotor and rotor supporting member, this longitudinal movement imparts rotary movement Vto the rods. The angular extent of rotation is controlled by changing the stroke of longitudinal movement, which, in turn, may be accomplished by varying the resiliency of the intermediate member or by adjustment which varies the extent of said members iexure.

The longitudinal movement of the rods in one direction is caused by the inertia of the plunger and rods or the imposition of added weight thereon (occurring at the start of the upstroke) at which time the resilient member is compressed; while the movement in the opposite direction is caused by expansion of the resilient member as the rods are relieved from this added weight or after their starting inertia is overcome (occurring, in main, at the end of the up stroke).

However, the actual rotation of the rod occurs only during the expansion of the resilient member, such expansion taking place, in main, when the added load is r.e-

leased from the rods, a feature of great' advantage since it reduces the wear and strains on the rotator, as well as reducing thetortional stresses and strains on the rods and plunger. Since the load is at a minimum during periods of rod rotation, little or no lubrication is required at points wher,e relative rotary movement occurs. The resilient member also acts as a shock absorber when the plunger changes motion at the start of its up stroke.

The rotator, as a whole, rests on or is suspended from the walking beam, but is not rigid therewith, so in the event the plunger becomes sanded in and resists further reciprocation, the beam may continue in its reciprocation without causing damage to the rotator, rods or plungers, for the rotator remains suspended on top the polish rod, and will be clear of the beam except when the latter is at the upper limit of its stroke.

Should the resistance .of the plunger to rotary movement exceed a predetermined value, we provide means whereby the reciprocation o the rods may continue without a coincident rotation thereof, lost motion then occurring between Ycertain cam elements of the device.

The weight of the rotator as directed on the rods is sufficient to aid in thrusting them through their down stroke, thus eliminatthe necessity of an adjuster board, alt ough the rotator weight is not sufficient to cause excess pressure on the rods when pum ing low' gravity oils.

W ile Vthe device is not complicated in construction, it is certain and positive of o eration, and may be installed with ease.

t is entirely self contained and has no operating connection to the beam or other part of the reciprocating mechanism which re uires loosening or detachment when the ro s are pulled from the well.

Other features of novelty and objects of the invention will be set forth in the followin detailed description, in which igure 1 is a diagrammatic view, in fragmentary and contracted elevation, of an oil well pump with our device attached thereto.

Fig. 2 shows our rotatormounted directly on the end of a walking beam.

Fig. 3 shows our rotator suspended from a walking beam by cables, the beam being shown in end elevation.

Fig. 4 shows the rotator mounted on the end of a jack which is adaptedf'to be operated by cribs or other connections from a pumping well.

Fig. 5 is a top plan view of our rotator.

Fig. 6 is an enlarged vertical section on line 6-6 of Figure 5.

Fig. 7 is a horizontal section on line 7--7 of Fig. 6.

Fig. 8 is a section on line 8-8 ofFigure 6, as viewed from below.

Fig. 9 is a. fragmentary Vview partially in section, as viewed from the line 9-9 of Figure 7; and

Fig. 10 is a view similar to Figure 9 but showing certain of the parts in changed relative position.

In Figure 1 is shown a pump barrel 10 at the lower end of tubing 11, the pump plunger 12 in barrel 10 being adapted to be reciprocated through the medium of sucker rods 13 which are coupled by threaded joints 14. The uppermost rod 15, commonly known as a polish rod has connection through rotator 16 with the reciprocating member 17 which, in Figures 1 and 2, comprises a walking beam, and in Figure L1 comprises a jack 17a. Beam 17 is fulcrumed on Samson post 18a, and is reciprocated through any of the well known crank means (not shown), while jack 17a is adapted to be reciprocated by any suitable connection (not shown) with a pumping well.

In order that rotator may be capable of attachment to the walking beam in a variety of manners or to beams of varying 4design, supporting member 18, which is of the general configuration of a bowl, has diametrically opposed rockers 19 on its. lower face, and diametricallyk opposed eyes 20 on its outer peripher Thus the rotator may be mounted on cams 17 or 17a so rockers 19 cradle in channeled bed plates 21, or may be suspended by stirrups or cables 22 which depend from the beams, the ends of the cable passing through eyes 20 and there secured, for instance, by being leaded in The flexible nature of either of these types of connection accommodates the relative' angular movement between beam and rotator during periods of pump operation.

Member 18 has a 4central opening 23 defined by a marginal, annular flange 24, which flange provides bearing for the tubular spindle 25 of rotor 26. The inner. bottom face of member 18 is cupped at 27 to receive and position a resilient member 28, which, in the present instance, is a rubber ring, thoiigh springs may be substituted for the ring without departing' from the scope of certain of our claims.

Resting on ring 26 is a load washer 29, cupped at 30 to receive the ring and having a central aperture 31 through which spindle 25 extends and has bearing. The upper face of washer 29 has a ball race 32, while the lower face of the annular rotor head 33 has a complementary ball race 34; balls 35 completing the ball bearing between head 33 and washer 29. Rotor 26 is held from separative movement with respect to washer 29 by ad,- justment nut 36 which is threaded into the central aperture 37 of cap 38, the annular flanges 39 of the latter being adapted to rest on the upwardly extending flanges of the bowl or supporting member 18. Bolts 41() (Figures 2 and 5) hold the cap and bowl in assembly.

Rotor 26 is positively connected to polish rod 15, the connection eing of any suitable type. For instance, the lower end of spindle 25 is threaded into cla'mp or grip 41 (see Figures 3 and 6) which, in turn, is rigidly clamped to rod 15 by any of the well known means such as wedge plug 42. In certain installations, especially where the rod extends through the forked end of a walking beam, a sleeve 43 about the rod may connect the clamp and rotor (see Figures 2 and 4). rl`he same effect may be gained by pinning the rotor to the polish rod, although the clamp method of attachment is preferable in that it does not mutilate' the rod and does provide a range of adjustment.

lt will be se'en from a consideration of the above assembly that the forces set up by the weight of the rod are transmitted to the walking beam through rotor 26, washer 29, ring 28, and supporting member 18. lVhen the rotator is in operative condition, ring 28.

is, of course, in a state of partial compression.

Now the addition of weight to the' rod, such as occurs when the plunger starts its up stroke and takes on a load of oil, causes the further compression of ring 28,. or, in effect, the supporting member initially moves upwardly more rapidly than does the rod and its attached rotor. Thus relative longitudinal movement between supporting member and rotor and-hence between be'am and rod, is set up. Then the rods are relieved of their additional load, as occurs at the end of the up, or delivery stroke, ring 28 flexes, due to its inherent resilient qualities, and moves rotor 33 and hence rod 15 upwardly with respect to the supporting member. thus completing a reciprocation of the rod with respect to the beam. lt is this relative longitudinal movement between rod and beam which we utilize to securethe. periodic rotation of rod 15.

Before going further into the rotating mechanism, we wish to call attention to the fact that relative longitudinal movementbetween rods and beam may also be set up by reason of the rods inertia, either when the direction of rod movement is reversed at the end of a stroke or when the rod is suddenly accelerated during the tip-stroke. Furthermore. lring 28 serves as aY shock absorber when the direction of rod movement is reversed at the end of the down stroke.

Rotor spindle 25 is continued above head 38 and has bearing in lbore 43 of adjustment nut 36, while the upper extremity of rod 15 is adapted to slide through the restricted bore 34 of said nut. Head 33, the topY of which is adapted to coact with nut 36 for stroke adjustment purposes, comprises an upper and lower annulus and 46, respectively. The upper face of annulus 46 is provided with serrations or teeth 47 and its peripheral face is provided with a plurality of cam lugs 48 having cam inclines 49. About annulus 45 is a rotor stop ring 50 having toothed segments 51 adapted to engage teetli 47. A particular and preferred arrangement of segments 51 will be discussed later. Stop ring 50 is capable of vertical movement within cap 38 but is held from rotary movement by link 51al which connects capstud 52 and ring stud 53, the latter pro- )ecting upwardly through the cap aperture faces 49 of rotor cams 48. A horse-shoe spring 59 has depending extremities 60 and 61 which extend through suitablezreceiving apertures in one of the rotor-cam lugs 48a and one of the follower cam lugs 57, respectively. 'Spring 59 has an inherent closing tendency, so it continuously exerts a yieldable effort to draw the follower cams into engagement with the rotor cams. Thus, as the rotor is moved in a manner to be presently described, spring 59 yieldably draws the follower after it, and maintains the complementary cams :in engagement.

A follower stop or ring 62 has toothed segments 63 which rest on and coact with the follower teeth 56. A stud 64 extends upwardly from follower stop 62 and through cap aperture 54, it being joined by link 64a to pin 65, this pin being slidably mounted in cap stud 66. A spring 67 on pin 65 between stud 66 and nut 68, forms a yieldable connection between ring 62 and cap 38 and normally prevents relative rotation therebetween, although it allows limited rotation 'under certain circumstances, as will be later set forth.

For the sake of brevity, we will confine the following description of the operation of the rotator to the instance where relative longitudinal movement between beam and rods is set up by the differential loading of the rods during their reciprocation. During the down stroke of the pump, all parts cf the mechanism are approximately in the relative position illustrated in the various figures of the drawings, excepting Figure 10.

When the additional load is placed on the rods as the pump starts its up stroke, ring 28 is further compressed and relative longitudinal movement between rotor 26 and supporting member 18 is set up. For the purpose of better pointingiroutlhe action of the device, we may assume that the movement of rotor 26 is downward with respect to member 18 during the period of such relative movement. As the rotor descends, rotor stop ring 50 moves with it, or at least descends sufficiently to maintain teeth 51 and 47 in partial mesh so counter-clockwise movement (as viewed in Figure 7) or backing up of the rotor is prevented. At the same time (that is, during one stage of relative longitudinal movement 'between rotor and supporting member) follower spring 59 causes follower ring 55 to move in a clockwise direction so it assumes the position of Figure 10, cams 48 and 57 being held continuously in sliding engagement, and the follower stop ring 62 ratcheting over follower teeth 56, said ring alternately` rising and dropping during such ratcheting. The parts remain in the position of Figure 10 until the load on the rods is reduced by the delivery of oil (disregarding, in this illustrative example, the matter of acceleration or change of motion of the rod) whereupon ring 28 iexes and raises the rods and rotor with respect to thesupporting member. Since the interengagement of teeth 63 and 56 normally prevent the counter-clockwise rotation or backing up of follower ring 55, rotor 26 is revolved in a clockwise direction (as viewed in Figure 7) by the coaction of cams "-48 with cams 57, spring 59 yielding to allow the relative rotary movement between the rotor and follower, it being evident that this rotation due to cam coaction occurs during another stage of relative longitudinal movement between rotor and supporting member. During such rotation, rotor stop ring 50 ratchets Vover rotor teeth 27, and subsequently holds the rotor against counterclockwise movement, said ring alternately rising and dropping the period of rotation.

Since the rotation of rotor 26 and polish rod 15 is in a clockwise direction as viewed from the top thereof, the threaded joints between sucker rods are tightened as a consequence, an obvious advantage.

Should the force necessary to rotate the rods and lunger exceed -a certain amount, as determined by the tension and adjustment of spring 67 through manipulation of nut 68 (Figure 5), cams 57 (and hence rings 55 and 62) are backed up by rotor cams 48, springs 59 and 67 yielding to allow this movement. Damage to the rotator and rods is thereby avoided, though the rods and rotor may still continue in their reciprocation. Should reciprocation of the plunge-r and rods be resisted to a dangerous degree, the rods and rotor remain stationary while the beam reciprocates idly. In such an event, where the rotator is-mounted as in Figures 2 and 4, the beam reciprocates idly beneath the rotator, while in the installation of Figure 3, the beam reciprocates idly above the rotator, the rotator being spaced below the beam a suicient distance to allow such idle reciprocation without interference.

By adjustment of nut 36, the extent of longitudinal movement of the rotor with respect to the supporting member may be regulated, for such adjustment fixes the allowable extent of fiexure of ring 28. By thus regulating the length of stroke, the angular extent of rod rotation during each reciprocation thereof, may be varied and regulated. Nut 36 is held in adjusted position by set screw 70 threaded through cap bracket 71 and adapted to engage notches .72 on the periphery of the nut.

By reason of th-e fact that rod rotation occurs only during periods when the load on and-resistance of the rods to reciprocating are diminishing or at a minimum, wear and strain on the rotator, rods and plunger is reduced to a minimum, and there is little or no need of providing lubrication between the rotor and load washer.

In Figure 8 we have illustrated a preferred method of arranging the locking segments on stop rings 50 and 62. Since both rings are of similar construction, but one need Vbe described in detail. The teeth in the various segments of a single ring are of equal pitch, but the groups of teeth are so spaced that the angular distance between pitch radii extended to similar points in the several segments is other than an even multiple of the circular pitch of said teeth. To

cite an example, and assuming that the seg- I ments of a given ring are of equal angular extent, the angular distance between pitch radii drawn to the centers of the segments are unequal. Thus, in Figure 8, the circular pitch of the teeth being 10o, we have shown the segments as being spaced apart 1231/30, 1231/30 and 1181/3". Only one segment is in operative engagement with the ratchet teeth of its companion rotating member at any one time.

By this relative arrangement of segments, or rather of teeth in the several segments, an operative engagement between rotating members and their respective locking rings may be obtained with less relative rotation than would be possible if all t-he segment teeth were spaced'in the manner usual to gear segments. Thus we secure the advantageous effects of a relatively small pitch ratchet wheel, as far as the extent of relative movement necessary to obtain proper interengagement is concerned, and yet have the advantage of the sizeable, strong teeth of a relatively large pitch ratchet wheel.

It will be noted that the rotator is entirely self-contained and may be installed and placed in operative condition with very little labor. The elimination of operating links, rods, etc., between rotator and beam is a feature of great value, for it obviates the necessity of loosening or detaching any such We have not attempted to discuss exhaustively all the advantageous results obtained by the use of our device, but we believe we have set forth a sufficient number of points to clearly indicate the superior quality or' our rotator. Wlhile we have shown and described a preferred embodiment of the invention, we do not wish to be limited thereto except for such limitations as a fair interpretation ofthe appended claims may import.

lVe claim:

1. In combination, a reciprocating mechanism, a member adapted to be reciprocated, means operatively connecting the mechanism and member whereby said member is reciprocated by operation of the mechanism, said connective means including two parts adapted to have relative rotative and longitudinal movement, a resilient member between the parts and adapted to yield and thereby allow relative longitudinal movement of the parts in given directions and subsequently, by virtue of its resiliency, to move the parts relatively and in opposite directions; and a drive connection between said parts and operable by virtue of their relative longitudinal movement to cause rotation of the parts in given relative directions, only.

2. ln combination, a reciprocating mechanism, a member adapted to be reciprocated, means operatively connecting the mechanism and member whereby said member is reciprocated by operation of the mechanism, said connective means including two parts adapt-- ed to have relative rotative and longitudinal movement, a resilient n. n the bet parts and adapted to yield the relative longitudinal movement of ie parts n given directions and subsequently, by virof its resiliency, more the parts rela-- Vfvely and in opposite directions; and a i able drive connection between said i and operable by virtue of their relative l isntudinal movement to cause rotation of the parts in given rela-tive directions, only, fl yieldable connection being adapted to and allow relative longitudinal movement of the parts without accompanying relative rotation thereof, when the torce necessary to cause such rotation exceeds a predetermined amount. v

In combination, a reciprocating mechanism, a member adapted to be reciproca-ted, means operatively connecting the mechanism and member whereby said member is reciprocated by operation of the mechanism, said connective means including two parts adapt-- ed to have relative rotative and longitudinal ',fievement, a resilient member between the s and adapted to yield and thereby allow 4ive longitudinal movement of the parts in. given directions and subsequently, by virtue ci its resiliency, to move the part-s relatively and in opposite directions; means4 adapted to hold the parts against relative rotation in given directions, and a drive connection between said parts and operable by virtue of their relative longitudinal movement to cause relative rotation of the parts in opposite directions.

4. ln combination, a walking beam, means for oscillating the walking beam, a supporting member on the beam, a polish rod, means connecting said member and rod in a manner whereby they are capable of rotation in given relative directions, only, and whereby oscillation of the beam reciprocates the rod, the resistance of the rod to reciprocation being variable; said connecting means including a resilient elementt adapted to yield,

when resistance of the rod increases, and thereby allow relative vertical movement of the member and rod in given directions, the element being further adapted to move the member and rod relatively and in opposite directions when the resistance of the rod subsequently decreases, and means operatively connecting said member and rod and operable by virtue of said relative movement to cause rotation of said rod with respect to said member.

5. In combination, a walking beam, means for oscillating the walking beam, a supporting member on the beam, a polish rod, means connecting said member and rod in a manner whereby they are capable of rotation in given relative directions, only, and whereby oscillation of the beam reciprocates 'the rod, the resistance of the rod to reciprocation being variable; said connecting means including a resilient element adapted to yield, when resistance of the rod increases, and thereby allow relativeV vertical movement of the member and rod in given directions, the element being further adapted to move the member and rod relatively and in opposite directions when the resistance of the rod subsequently decreases; adjustable means for regulating the allowable extent of relative longitudinal movement between the member and rod, and means operatively connecting said member and rod and operable by virtue of said relative movement to cause rotation of said rod with respect to said member. f

6. In combination, a reciprocating mechanism, a member adapted to be reciprocated, means operatively connecting the mechanism and member whereby said member is reciprocated by operation of the mechanism, said connective means including two parte adapted to have relative rotative and longitudinal movement, a resilient member between the parts and adapted to yield and thereby allow relative longitudinal movement of the parts in given directions and subsequently, by virtue of its resiliency to move the parts relatively and in opposite directions;' and a yieldable and adjustable drive connection between said parts' iand operable by virtue of their relative longitudinal movement to cause rotation of the parts in given relative directions, only.

7. In a device of the character described, a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movable both rotatably and logitudinally with respect to the supporting member, said resilientmember yieldably resisting longitudinal movement of the rotor in one direction, acam on the rotor, and a cam supported by the supporting member, one of said cams having a face extending an larly with respect to the axis 4of rotatlon of the rotor, said cams being so relatively arranged that the other cams engages said angular face during longitudinal movement of the rotor in the other direction and thereby sets up rotation of the rotor with respect to the supporting member.

8. In a device of the character described, a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movable both rotatably and longitudinally with respect to the supporting member, a stop member holding the rotor-against rotation in one direction with respect to the supporting member, said resilient member yieldably resisting longitudinal movement of the rotor in one direction, a cam on the rotor, and a cam supported by the supporting member, one of said cams having a face extending angularly with respect to the axis of rotation of the rotor, said cams being so relatively arranged that the other cam engages said angular face during longitudinal movement of the rotor in the other direction and thereby sets up rotation of the rotor in the opposite direction With respect to the supporting member.

9. In a device of the character described, a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movable both rotatably and longitudinally with respect-to the supporting member, a stop member supported by the supporting member and holding the rotor against rotation in one direction with respect to the supporting member, said resilient member yieldably resisting longitudinal movement of the rotor in one direction, a cam on the rotor, and a cam supported by the. supporting member, one of said cams having a face extending angularly with respect to the axis of rotation-of the rotor, said cams being so relatively" arranged that the other cam engages said angular face during longitudinal movement of the rotor in the other direction and thereby sets up rotation of the rotor in the opposite direction with respect to the supporting member.

10. In a device of the character described, l

a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movab e both rotatabl and longitudinally with respect to the su porting member, a follower or tl\1e\otor and supported normally for rtation in one direction only, with respect to the supporting member, a cam on the follower, one of said cams having a face extending angularly with respect to the axis of rotation of the rotor, said cams being so relatively arranged that the other cam engages said angular face during longitudinal movement of the rotor in the other direction and therebyl sets up rotation of the rotorin one direction with respect to the supporting member, and means holding the rotor against rotation in the other direction.

11. In a device of the character described, a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movable both rotatably and longitudinally with respect to the supporting member, said resilient member yieldably resisting longitudinal movement of the rotor in one direction, a cam on the rotor, a follower for the rotor and supported for rotation with respect to the supporting member, yieldable means adapted to hold the follower against rotation in one direction, a cam-on the follower, one of said cams having a face extending angularly with Irespect to the axis of rotation of the rotor, said cams being so relativel arranged that the other cam engages sald angular face during longitudinalk movement of the rotor in the other direction and thereby sets up rotation of the rotor in one direction with respect to the supporting member, and means holdin the rotor against rotation in the other irection.

12. In a device of the character described, a supporting member, a resilient member supported by the supporting member, a rotor supported on the resilient member and movable both rotatably and longitudinally with respect to the sup orting member, said resilient member yieldrably resisting longitudinal movement of the rotor in one direction, a cam om the rotor, a follower for the rotor and supported for rotation with respect to the supporting member, yieldable means adapted to hold the follower against rotation in one direction, a connectlon between tion and thereby sets up rotation of the rotor in one direction with respect to the supporting member, and means holdingV the rotor against rotation in the other direction.

13. In a device of the character described, a rotor having arcuately arranged ratchet teeth, a coaxial member having a plurality of ntoothed segments adapted independently to cooperate with the ratchet teeth, the circular pitch of the ratchet and segment teeth being equal and the angular distance be tween radii extended to similar points of teeth in any two segments being other than an even multiple of the circular pitch of said,

teeth, the rotor and member being relatively rotatable to bring the segments successively into operative engagement with the ratchet teeth, and means for rotating the rotor.

14. In a device ofthe character described, a supporting member, a resilient element supported by said member, a rotor yieldably supported on the resilient element, said rotor including a head, peripheralcams on the head, a rotatable follower ring supported on the supporting member, cams on the inner peripheral face of the ring engaging the rotor cams, means for holding the follower ring against rotation in one direction, and rotor-driven means adapted` to rotate said ring inthe opposite direction when the re-Y silient member yields beneath the rotor.

15. In a device of the character described, a supporting member, a resilient element supported by said member, a rotor yieldably supported on the resilient element, adjusta Y ble means compressino` the resilient element between the rotor and supporting member,.

said rotor including a head, peripheral cams on the head, a rotatable follower ring supported on the supporting member, cams on the inner peripheral-face of the ring engaging the rotor cams, means holding the fol- Y lower ring against rotation in one direction,

and rotor-driven means adapted to rotate said ring in the opposite direction when the resilient member yields beneath the rotor,

16. In a device of the characterdescribed, a supporting member, a resilient element, supported by said member, a rotor yieldably supported on the resilient element, said rotor including a head, peripheral cams on thel head, ratchet teeth on top the head, a rotor-stop member carried by the supporting member and having ratchet engagement with said teeth, a rotatable follower ring supported on the supporting member, cams on the inner peripheral face of the ring and engaging the rotor cams, means holding the follower ring against rotation in one direction, and rotor-driven means adapted to rotate said ring in the opposite direction when the resilient member yields Ybeneath the rotor; the rotor-stop member being adapted to hold said rotor against rotation in said one direction.

17. In a device of the character described, a supporting member, an annular resilient element supported by said member, a wear washer on top the resilient element, ball bearings on top the wear washer, and a rotor rotatably supported by said bearings, and mlans for connecting said rotor to a polish ro i 18. In a device of the character described, a bowl-shaped supporting member having a central aperture in its bottom wall, a ringshaped resilient element in the bowl, and a YYrotor above and supported by the resilient member, said rotor including a spindle eX- tending downwardly through the apertures of the ring and bottom wall and having rotational bearing in said bottom wall.

19. In a device of the character described, a bowl-shaped supporting member having a central aperture in its bottom wall, a ringshaped resilient element in the bowl, a rotor above and supported by the resilient member, said rotor including a spindle extending downwardly through the apertures of the ring and bottoni wall, and a rod grip on the spindle below said bottom wall.

20. In a device of the character described, a bowl-shaped supporting member having a central aperture in its bottom wall, a ringshaped resilient element in the bowl, a rotor above and supported by the resilient mem- 

